{
  "abstract": "The DESI DR2 collaboration reported $\\sim 4\\sigma$ evidence for evolving dark energy ($w_0 \\gt -1$, $w_a \\lt 0$) from baryon acoustic oscillations (BAO) combined with Type Ia supernova (SN Ia) distances. A persistent concern is whether low-redshift SN calibration systematics drive this signal. We introduce a redshift truncation scan – progressively excising low-z SNe and re-fitting CPL cosmology – and apply it to three SN data sets with independent absolute calibrations: Pantheon+ (SH0ES Cepheid distance ladder), DESY5 (internal BAO-anchored calibration), and DES-Dovekie (white dwarf SEDs + Gaia spectrophotometry). All chains use the full Planck 2018 TTTEEE_lite likelihood. We show that the signal is not dominated by photometric calibration. DES-Dovekie serves as a positive control: its CPL signal, already weakened by the recalibration, collapses under truncation – the signature of a calibration-driven signal. In contrast, Pantheon+ and DESY5 retain a $\\sim 2\\sigma$ deviation ($\\Delta \\chi ^2 \\approx 4$) after all $z \\le 0.12$ SNe are removed that does not weaken with further truncation. Quantitatively, in $\\chi ^2$ space the signal decomposes into photometric calibration ($\\Delta \\chi ^2 = 7.6$, $2.8\\sigma$) and low-z non-calibration ($\\Delta \\chi ^2 = 7.4$, $2.7\\sigma$), which together with a residual consistent with the CMB+BAO baseline ($\\Delta \\chi ^2 \\approx 2$, $1.4\\sigma$) reproduce the DESY5 total ($4.0\\sigma$) to within a few per cent. This truncation-immune residual is either genuine dark energy evolution or a shared SN Ia standardization systematic beyond calibration.",
  "abstract_shown": true,
  "affiliations": [
    "Independent Researcher , Ningbo, 315336 ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Tao Zhang",
      "orcid": "0009-0000-5067-0887"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/edf8pqfjnwhk5.bib",
  "cited_by": 0,
  "doi": "10.1093/mnras/stag1868",
  "fulltext_url": null,
  "id": "edf8pqfjnwhk5",
  "issns": [
    "0035-8711",
    "1365-2966"
  ],
  "landing_url": "https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1868/8855714",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7214923101",
  "pdf_url": "https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag1868/71532305/stag1868.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-30",
  "publisher": "Oxford University Press (OUP)",
  "ris": "https://research.draconitic.com/paper/edf8pqfjnwhk5.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:17Z",
      "native_id": "10.1093/mnras/stag1868",
      "source": "crossref",
      "url": "https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1868/8855714"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Cosmology and Gravitation Theories",
      "subfield": "cosmology"
    }
  ],
  "title": "A truncation test of the DESI evolving dark energy signal: three supernova calibrations compared",
  "title_text": "A truncation test of the DESI evolving dark energy signal: three supernova calibrations compared",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:17Z",
  "url": "https://research.draconitic.com/paper/edf8pqfjnwhk5",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": []
}